<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <style>
        .box1 {
            width: 200px;
            height: 100px;
            background-color: deepskyblue;
            /* 挨个设置某一边的圆角 */
            /* border-top-left-radius: 50px;
            border-bottom-right-radius: 50px; */

            /* 一次性给四个角都设置圆角 */
            border-radius: 50px;
        }
        .box2 {
            width: 200px;
            height: 200px;
            background-color: pink;
            /* 圆形 */
            border-radius: 50%;
        }
    </style>
    <title>Document</title>
</head>
<body>
    <div class="box1"></div>
    <div class="box2"></div>
</body>
</html>